Photodiode, optical communication device, and optical interconnection module

Abstract

Intended is to provide a device structure, which makes the light receiving sensitivity and the high speediness of a photodiode compatible. Also provided is a Schottky barrier type photodiode having a conductive layer formed on the surface of a semiconductor layer. The photodiode is so constituted that a light can be incident on the back side of the semiconductor layer, and that a periodic structure, in which a light incident from the back side of the semiconductor layer causes a surface plasmon resonance, is made around the Schottky junction of the photodiode.

1 - 26 . (canceled) 
     
     
         27 - 53 . (canceled) 
     
     
         54 . A photodiode having a semiconductor layer and a conductive layer:
 wherein a periodic structure for causing a surface plasmon resonance is formed adjacently to said conductive layer in a circumference of a junction of said photodiode;   wherein said semiconductor layer is formed on a surface in which said periodic structure of said conductive layer has been formed;   wherein a dielectric layer of which a refractive index is lower than that of said semiconductor layer is formed around said semiconductor layer; and   wherein said photodiode is configured so that light can be incident on a surface in which said periodic structure has been made.   
     
     
         55 . The photodiode as claimed in  claim 54 ;
 wherein said photodiode is a Schottky junction type photodiode having said conductive layer formed on a surface of said semiconductor; and   wherein said periodic structure for causing the surface plasmon resonance is formed adjacently to said conductive layer in a circumference of a Schottky junction of said Schottky junction type photodiode.   
     
     
         56 . The photodiode as claimed in  claim 54 ;
 wherein said photodiode is a p-i-n type photodiode formed on a surface of said semiconductor layer:   wherein said conductive layer is formed around a p-i-n junction of said p-i-n type photodiode; and   wherein said periodic structure for causing the surface plasmon resonance is formed around the p-i-n junction of said p-i-n type photodiode, and yet adjacently to said conductive layer.   
     
     
         57 . The photodiode as claimed in  claim 54 ;
 wherein said photodiode is a photodiode having metal-semiconductor-metal junctions intervally arranged on a surface of said semiconductor layer:   wherein said conductive layer is formed around a metal-semiconductor-metal junction of said photodiode; and   wherein said periodic structure for causing the surface plasmon resonance is formed around the metal-semiconductor-metal junction of said photodiode, and yet adjacently to said conductive layer.   
     
     
         58 . The photodiode as claimed in  claim 57 ;
 wherein an interval of said metal-semiconductor-metal junctions arranged on the surface of said semiconductor layer is equal to or less than λ/n (where λ: a wavelength of the light incident from the back side of the semiconductor layer, and n: a refractive index of the light in the semiconductor layer); and   wherein said metal layer is a layer in which a metal layer forming a Schottky junction with said semiconductor, and a layer comprised of a conductive material capable of inducing a surface plasmon have been laminated, or a metal layer capable of forming the Schottky junction with said semiconductor, and yet of inducing the surface plasmon.   
     
     
         59 . The photodiode as claimed in  claim 57 , wherein, with respect to said metal-semiconductor-metal junction, at least one of metal-semiconductor junctions facing each other is a Schottky junction. 
     
     
         60 . The photodiode as claimed in  claim 54 , wherein said periodic structure for causing the surface plasmon resonance is a structure in which said conductive layers capable of inducing the surface plasmon have been laminated on the surface of said semiconductor layer having roughness formed thereon. 
     
     
         61 . The photodiode as claimed in  claim 54 , wherein said periodic structure for causing the surface plasmon resonance is a structure in which said conductive layers capable of inducing the surface plasmon have been laminated on the surface of said dielectric layer having roughness formed thereon. 
     
     
         62 . The photodiode as claimed in  claim 54 , wherein the periodic structure for preventing the surface plasmon resonance from being generated is made outside said periodic structure for causing the surface plasmon resonance. 
     
     
         63 . The photodiode as claimed in  claim 54 , wherein a stepped structure for reflecting the surface plasmon is made outside said periodic structure for causing the surface plasmon resonance. 
     
     
         64 . The photodiode as claimed in  claim 63 , wherein said stepped structure is comprised of a projected shape higher than λ/n d  (where n d  is a refractive index of the light in the semiconductor layer or the dielectric layer neighboring a conductive film and λ is a wavelength of the light). 
     
     
         65 . The photodiode as claimed in  claim 63 , wherein said stepped structure is comprised of a grooved shape deeper than λ/n d  (where n d  is a refractive index of the light in the semiconductor layer or the dielectric layer neighboring the conductive film and λ is a wavelength of the light). 
     
     
         66 . The photodiode as claimed in  claim 63 , wherein said stepped structure is comprised of a shape formed in the conductive material, said shape having bores of which a diameter is equal to or smaller than the wavelength of the incident light arrayed thereon. 
     
     
         67 . The photodiode as claimed in  claim 63 , wherein said stepped structure is comprised of a shape formed in the conductive material, said shape having slits of which a width is equal to or smaller than the wavelength of the incident light arrayed thereon. 
     
     
         68 . The photodiode as claimed in  claim 54 , wherein said conductive layer is configured of at least one metal selected from a group consisting of Al, Ag, Au and, Cu, or an alloy thereof. 
     
     
         69 . The photodiode as claimed in  claim 54 , wherein a junction area in said photodiode is 100 square microns or less. 
     
     
         70 . The photodiode as claimed in  claim 54 , wherein a junction area in said photodiode is 10 square microns or less. 
     
     
         71 . The photodiode as claimed in  claim 54 , wherein a junction area in said photodiode is one square micron or less. 
     
     
         72 . The photodiode as claimed in  claim 54 , wherein a thickness of the semiconductor absorption layer in said photodiode is 1 μm or less. 
     
     
         73 . The photodiode as claimed in  claim 54 , wherein a thickness of the semiconductor absorption layer in said photodiode is 200 nm or less. 
     
     
         74 . The photodiode as claimed in  claim 54 , wherein the semiconductor absorption layer in said photodiode is configured of at least one member selected from a group consisting of Si, SixGel-x (where x is a positive number less than 1), Ge, GaN, GaAs, GalnAs, GaInP, and InP. 
     
     
         75 . The photodiode as claimed in  claim 54 :
 wherein the semiconductor absorption layer in said photodiode is configured of at least one member selected from a group consisting of Ge, and SixGel-x (where x is a positive number less than 1); and   wherein a layer comprised of an alloy of Ni and Ge is formed between said semiconductor absorption layer and said conductive layer.   
     
     
         76 . The photodiode as claimed in  claim 54 , said photodiode configured on an optical waveguide comprised of the semiconductor. 
     
     
         77 . The photodiode as claimed in  claim 54 , said photodiode configured so that it can receives the light from the optical waveguide formed on a substrate side, said light reflected by a mirror. 
     
     
         78 . The photodiode as claimed in  claim 54 , wherein a substrate of said photodiode is configured of a material transparent to the incident light. 
     
     
         79 . An optical communication device, wherein said photodiode of  claim 54  is formed on a light receiving portion. 
     
     
         80 . An optical interconnection module, comprising:
 a Si substrate having said photodiode of  claim 54  configured thereon; and an LSI electronic circuit formed monolithically with said photodiode on said Si substrate.